REFACTOR: support custom order by column

pkg/service/trade.go

@@ -2,6 +2,7 @@ package service
 
 import (
 	"context"
+	"fmt"
 	"strconv"
 	"strings"
 	"time"
@@ -32,7 +33,11 @@ type QueryTradesOptions struct {
 
 	// ASC or DESC
 	Ordering string
-	Limit    uint64
+
+	// OrderByColumn is the column name to order by
+	// Currently we only support traded_at and gid column.
+	OrderByColumn string
+	Limit         uint64
 }
 
 type TradingVolume struct {
@@ -304,12 +309,29 @@ func (s *TradeService) Query(options QueryTradesOptions) ([]types.Trade, error)
 		sel = sel.Where(sq.Eq{"exchange": options.Sessions})
 	}
 
-	if options.Ordering != "" {
-		sel = sel.OrderBy("traded_at " + options.Ordering)
-	} else {
-		sel = sel.OrderBy("traded_at ASC")
+	var orderByColumn string
+	switch options.OrderByColumn {
+	case "":
+		orderByColumn = "traded_at"
+	case "traded_at", "gid":
+		orderByColumn = options.OrderByColumn
+	default:
+		return nil, fmt.Errorf("invalid order by column: %s", options.OrderByColumn)
+	}
+
+	var ordering string
+
+	switch strings.ToUpper(options.Ordering) {
+	case "":
+		ordering = "ASC"
+	case "ASC", "DESC":
+		ordering = strings.ToUpper(options.Ordering)
+	default:
+		return nil, fmt.Errorf("invalid ordering: %s", options.Ordering)
 	}
 
+	sel = sel.OrderBy(orderByColumn + " " + ordering)
+
 	if options.Limit > 0 {
 		sel = sel.Limit(options.Limit)
 	}

pkg/service/trade_test.go

@@ -1,9 +1,11 @@
 package service
 
 import (
+	"database/sql"
 	"testing"
 	"time"
 
+	"github.com/DATA-DOG/go-sqlmock"
 	"github.com/jmoiron/sqlx"
 	"github.com/stretchr/testify/assert"
 
@@ -87,3 +89,36 @@ func Test_queryTradesSQL(t *testing.T) {
 		}))
 	})
 }
+
+func TestTradeService_Query(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	if !assert.NoError(t, err) {
+		return
+	}
+	defer db.Close()
+
+	sqlxDB := sqlx.NewDb(db, "mysql")
+	defer sqlxDB.Close()
+
+	s := NewTradeService(sqlxDB)
+
+	_, err = s.Query(QueryTradesOptions{Ordering: "test_ordering"})
+	assert.Error(t, err)
+	assert.Equal(t, "invalid ordering: test_ordering", err.Error())
+
+	_, err = s.Query(QueryTradesOptions{OrderByColumn: "invalid_column"})
+	assert.Error(t, err)
+	assert.Equal(t, "invalid order by column: invalid_column", err.Error())
+
+	mock.ExpectQuery("SELECT \\* FROM trades WHERE gid > \\? ORDER BY gid ASC").WithArgs(1234).WillReturnError(sql.ErrNoRows)
+	_, err = s.Query(QueryTradesOptions{LastGID: 1234, Ordering: "ASC", OrderByColumn: "gid"})
+	assert.Equal(t, sql.ErrNoRows, err)
+
+	mock.ExpectQuery("SELECT \\* FROM trades ORDER BY gid DESC").WillReturnError(sql.ErrNoRows)
+	_, err = s.Query(QueryTradesOptions{Ordering: "DESC", OrderByColumn: "gid"})
+	assert.Equal(t, sql.ErrNoRows, err)
+
+	mock.ExpectQuery("SELECT \\* FROM trades ORDER BY traded_at ASC").WillReturnError(sql.ErrNoRows)
+	_, err = s.Query(QueryTradesOptions{Ordering: "ASC", OrderByColumn: "traded_at"})
+	assert.Equal(t, sql.ErrNoRows, err)
+}